120-10 Geological mapping and airborne geophysics in the Alabama graphite belt

Abstract:

The Alabama graphite belt, located in east-central Alabama, potentially hosts the most geographically extensive high-grade flake graphite deposits in the conterminous Unites States. The belt is lithologically and structurally complex, containing numerous faults and folds, each of which can control graphite concentration and quality. Graphite in the belt occurs as disseminated flakes in schist, gneiss, and quartzite. However, the extent of these graphitic lithologies in the belt is poorly constrained due to a paucity of detailed geologic mapping in the region.

The Geological Survey of Alabama (GSA), in partnership with the U.S. Geological Survey (USGS) Earth Mapping Resources Initiative (Earth MRI), has conducted two mapping projects in the Alabama graphite belt. The GSA has completed detailed geologic maps in an area that hosts past producing graphite mines (Flag Mountain and Mitchell Dam 7.5-minute quadrangles) and is completing maps in an area that is underexplored for graphite (Micaville, Newell, and Wedowee 7.5-minute quadrangles). Mapping results confirm the belt experienced prograde upper-amphibolite facies metamorphism and deformation followed by retrograde greenschist facies and concomitant deformation. Newly identified kilometer-scale isoclinal folds contain discontinuous layers of partially melted graphitic schist and gneiss that pinch and swell along strike. Detailed 1:24,000-scale mapping revealed textural evidence that suggests graphite may be concentrated in areas of anatexis and deformation.

Recent high-quality airborne geophysical surveys (electromagnetic, magnetic, and radiometric) have been flown over the Alabama graphite belt in conjunction with Earth MRI projects. Graphite-bearing units are more electromagnetically conductive and have radiometric and magnetic signatures that differ from surrounding lithologies. These data greatly assist with mapping in the region by highlighting graphitic lithologies and identifying cryptic structures that are otherwise difficult to trace due to dense vegetation cover and poor exposure. For example, several new foliation-parallel faults and late brittle faults that cross the foliation and lithologies have been identified by studying all three geophysical datasets. Additionally, these data provide important information on the locations and, in some cases, existence of major faults and other structures in the area, such as the Goodwater-Enitachopco and Alexander City faults. These maps and geophysical data will serve as valuable precompetitive data to industry and academia and will be key in deciphering the assembly of the southern Appalachian orogen.

Geological Society of America Abstracts with Programs. Vol. 58, No. 5, 2026

doi: 10.1130/abs/2026AM-17856

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